Diagnosed with ALS (Lou Gehrig's Disease) back in 2011, Gleason has been a tireless and inspirational advocate for ALS research, while also doing utterly cool things, like climbing Machu Pichu and hanging out with Pearl Jam. Now, his story is the subject of a feature documentary, entitled Gleason that is set to debut at next week's Sundance Film Festival in Park City, Utah. The film has received substantial funding and could very well make a theatrical run, depending on how things go at Sundance.

The film has been long in the making, and follows him through his playing days, into fatherhood and then, of course, his ongoing battle with ALS. Here's a tear-jerking clip courtesy of Sports Illustrated with Gleason talking to his then-unborn son Rivers.